Diesel fuel emulsion

ABSTRACT

A fuel emulsion consists of diesel, water and an emulsifier composition having a hydrophile/lipophile balance value of at least 4. The emulsifier composition comprises a polymeric non-ionic surfactant having hydrophilic and hydrophobic repeating units together with at least one component selected from fatty acid esters or partial esters of polyhydric alcohols; alkoxylated fatty acid esters or partial esters of polyhydric alcohols; and alkoxylated primary alcohols. Preferred emulsifier compositions according to the invention include mixtures of the polymeric non-ionic surfactant with at least two of the components. Especially preferred compositions comprise mixtures of the polymeric non-ionic surfactant with the fatty acid (partial) esters or alkoxylated fatty acid (partial) esters. The emulsifier composition may include an emulsion coupler such as a primary alcohol, e.g. octanol.

The invention relates to fuel emulsions and to emulsifier compositionsfor use therein.

Diesel engines are used in a wide variety of applications includingautomotive, marine, electricity generation and compressors. Such enginesare often relatively inefficient and emit significant quantities ofpollutant gases and particles. This is of particular concern when theengines are in public service vehicles such as buses and the resultantpollution affects significant numbers of people in town centres.

To increase the efficiency with which the diesel fuel is burnt in suchengines and to reduce the generation of pollutants, water is added tothe diesel to form an emulsion therewith. Typically, such emulsionscontain at least 80% by weight diesel and up to 15% by weight of water(the weight percentages being based on the total weight of thecomposition). As water and oils such as diesel do not naturally mix, itis necessary to use emulsifiers in the water/diesel mixture to aid theformation and retention of emulsions. The emulsifiers are typicallypresent in amounts up to 6% by weight based on the total weight of thecomposition.

Diesel fuels also typically include additives for various purposes. Forexample, such fuels may contain cetane number improvers, eg nitrates,nitro and nitroso compounds and peroxides, at levels of up to 0.3% byweight. Dispersants and detergents, for example low molecular weightamines, are used to improve engine cleanliness. To improve the lowtemperature properties of the fuel, cold flow blending agents, egkerosene, may be added in quantities up to several percent to dilute theformation of wax crystals. Additionally, cold flow additives, egethylene-vinyl ester copolymers, chlorinated hydrocarbons andpolyolefins, may be used at ppm levels to alter the formation of waxcrystals.

Other additives may include oxygenates, eg rapeseed oil methyl ester, toimprove fuel combustion characteristics; antioxidants, eg amines andother nitrogen-containing compounds, to improve the long term stabilityof the fuel with respect to colour and sediment formation; lubricityaids and metal deactivators.

Owing to the shelf life requirement for such water/diesel fuel emulsions(from blending to use in an engine), a primary requirement for theemulsions is that they are stable for a minimum period, ie 10,000minutes (1 week). Another primary requirement for the fuel emulsions isthat they are competitively priced in the relevant markets;consequently, any additives such as emulsifiers need to be used inminimum amounts and/or be as inexpensive as possible.

Current water/diesel fuel formulations use simple, low-cost emulsifierssuch as partial esters of polyhydric alcohols at relatively high levels,eg 4% to 6% by weight. However, such emulsifiers at those levels mayresult in deposits being formed within engines leading to greaterinefficiency of operation.

Known water/diesel fuel formulations are disclosed in WO 85/04183 A1, WO00/63322 A1, WO 01/02516 A1, U.S. Pat. No. 3,876,391, GB-A-2066288,GB-A-2352246, EP-B1-0012292, EP-B1-0242832, EP-B1-0372353,EP-B1-0888421, EP-A1-0893488, EP-A2-1101815, DE-A-3229918, CN 1079499and JP-B2-2793190.

It is an object of the present invention to provide a stable,cost-effective fuel emulsion and emulsifier compositions for use in fuelemulsions.

According to the present invention, a fuel emulsion comprises awater-in-diesel emulsion containing an emulsifier composition in anamount effective to form a stable emulsion, the emulsifier compositioncomprising a polymeric non-ionic surfactant having hydrophilic andhydrophobic repeating units together with at least one componentselected from:—

-   a) fatty acid esters or partial esters of polyhydric alcohols;-   b) alkoxylated fatty acid esters or partial esters of polyhydric    alcohols; and-   c) alkoxylated primary alcohols;    the polymeric non-ionic surfactant and said at least one component    being selected such that the emulsifier composition has an    hydrophile/lipophile balance value of at least 4 and, more    preferably at least 5.

The hydrophile/lipophile balance (HLB) of surfactants is described inPreservation of Surfactant Formulations, Ed F F Morpeth, Published byBlackie Academic & Professional, 1995, Ch 4, Section 4.5, p77 et al.

The invention also includes an emulsifier composition for use in fuelemulsions, which composition comprises a polymeric non-ionic surfactanthaving hydrophilic and hydrophobic repeating units together with atleast one component selected from:—

-   a) fatty acid esters or partial esters of polyhydric alcohols;-   b) alkoxylated fatty acid esters or partial esters of polyhydric    alcohols; and-   c) alkoxylated primary alcohols;    the polymeric non-ionic surfactant and said at leas one component    being selected such that the emulsifier composition has an    hydrophile/lipophile balance value of at least 4 and, more    preferably at least 5.

Preferred emulsifier compositions according to the invention have anhydrophile/lipophile balance value of not more than 8 and, morepreferably not more than 7 and more especially not more than 6.

Preferably, the fuel emulsion according to the invention contains atleast 70% by weight diesel and up to 25%, more particularly around 10%to 20%, by weight of water, the weight percentages being based on thetotal weight of the emulsion.

The fuel emulsion may also contain conventional additives as previouslydiscussed.

Preferably, the fuel emulsion comprises an amount of emulsifiercomposition in the range 0.1% to 4% by weight of the total weight of thecomposition; more preferably, an amount of emulsifier composition in therange 1% to 3% by weight; and especially an amount in the range 1% to2.5% by weight.

Preferably, the polymeric non-ionic surfactant has an HLB of between 4and 13, more preferably between 4 and 8. The polymeric non-ionicsurfactant is preferably a polyester. Preferably, the hydrophilic unitsare polyoxyalkylene units, especially polyoxyethylene units; and thehydrophobic units are long chain hydrocarbon residues. Suitablepolymeric non-ionic surfactants of this type are available from Uniqemaunder the trade mark Hypermer (Hypermer is a trade mark owned by the ICIgroup of companies).

Preferably, component a) is the reaction product of one or morepolyhydric alcohols and one or more fatty acids. The ester reactionproducts may be monoesters or di-, tri- or higher esters or partialesters or mixtures thereof.

More particularly, the polyhydric alcohols comprise glycols, ie dihydricalcohols, and higher alcohols such as glycerol, sorbitol and neopentylalcohols such as trimethylol propane, pentaerythritol, neopentyl glycoland oligomers thereof such as di-trimethylol propane, tri-trimethylolpropane, di-pentaerythritol and tri-pentaerythritol and mixtures of twoor more thereof. More especially, the polyhydric alcohols comprisealcohols having at least three hydroxyl groups such as glycerol andsorbitol and preferably are sorbitol.

The fatty acid comprises a C₁₂ to C₂₄, straight or branched chain,saturated or unsaturated acid such as myristic, palmitic; isopalmitic,stearic, isostearic, oleic and linoleic acids or mixtures thereof. Moreespecially, the fatty acid comprises a C₁₆ to C₂₀ straight chain acidsuch as stearic or oleic acid and preferably it is oleic acid.

Examples of component a) are sorbitan monolaurate, sorbitanmonopalmilate, sorbitan monosterate, sorbitan tristerate; sorbitansesquioleate, sorbitan monooleate and sorbitan trioleate. Suitableesters of this type are available from Uniqema under the trade mark Span(Span is a trade mark owned by the ICI group of companies).

Preferably, component b) is the reaction product of at least onecomponent a) ester with an alkylene oxide.

Component a) esters are preferably alkoxylated using ethylene oxide orpropylene oxide; especially ethylene oxide. In particular, the estersare alkoxylated with not more than 50 moles of alkylene oxide,preferably not more than 30 moles of alkylene oxide

Examples of component b) are polyoxyethylene versions of sorbitanmonolaurate, sorbitan monopalmilate, sorbitan monosterate, sorbitantristerate, sorbitan sesquioleate, sorbitan monooleate, and sorbitantrioleate. Suitable alkoxylated esters of this type are available fromUniqema under the trade mark Tween (Tween is a trade mark owned by theICI group of companies).

Preferred component c) alkoxylated primary alcohols are derived fromC₇-C₂₀, more especially from C₉ to C₁₅, primary alcohols or mixturesthereof. The primary alcohols are preferably alkoxylated using ethyleneoxide or propylene oxide; especially ethylene oxide. In particular, thealcohols are alkoxylated with not more than 50 moles of alkylene oxide,preferably not more than 30 moles of alkylene oxide.

Examples of component c) are polyoxyethylene versions of C₉/C₁₁ andC₁₃/C₁₅ mixtures of primary alcohols. Suitable alkoxylated primaryalcohols are available from Uniqema under the trade mark Synperonic(Synperonic is a trade mark owned by the ICI group of companies).

Other components that function as emulsion couplers may also be used inthe emulsifier compositions of the invention. For example, a primaryalcohol may be added to the composition. The primary alcohol may beadded in amounts up to 5% by weight, more preferably up to 3% by weightof the emulsifier composition. The primary alcohol is preferablyselected from C₅ to C₁₅ more especially C₆ to C₁₂, primary alcohols andis typically octanol.

Preferred emulsifier compositions according to the invention includemixtures of the polymeric non-ionic surfactant with at least twocomponents selected from components a), b) and c). Mixtures ofcomponents a) and b) comprise especially preferred compositions of theinvention.

Preferred emulsifier compositions according to the invention comprisenot more than 50% by weight, based on the total weight of the emulsifiercomposition, more preferably between 1% and 30%, and more especiallybetween 2.5% and 20% of the polymeric non-ionic surfactant incombination with at least one of components a), b) and c). Moreespecially, emulsifier compositions comprise the polymeric non-ionicsurfactant in combination with at least two of components a), b) and c).The most preferred emulsifier compositions comprise the polymericnon-ionic surfactant in combination with components a) and b).Preferably, the emulsifier compositions are formulated to have an HLB inthe range 5 to 6.

The present invention includes a method of making a fuel emulsion whichcomprises a water-in-diesel emulsion containing an emulsifiercomposition in an amount effective to form a stable emulsion, theemulsifier composition comprising a polymeric non-ionic surfactanthaving hydrophilic and hydrophobic repeating units together with atleast one component selected from:—

-   a) fatty acid esters or partial esters of polyhydric alcohols;-   b) alkoxylated fatty acid esters or partial esters of polyhydric    alcohols; and-   c) alkoxylated primary alcohols;    the polymeric non-ionic surfactant and said at least one component    being selected such that the emulsifier composition has an    hydrophobe/lipophobe balance value of at least 4 and, more    preferably at least 5, which method comprises, in a single mixing    operation introducing diesel and the emulsifier composition and then    water into a mixing vessel whilst subjecting the mixture to high    shear mixing at a speed and for a period sufficient to create the    emulsions

The invention will now be described further by way of example only withreference to the following Examples.

EXAMPLE 1

Samples of emulsifier compositions were prepared by mixing, in a beaker,specific amounts of a polymeric non-ionic surfactant and components a)and b) as defined above. The components used in the emulsifiercompositions are identified in Table 1 below and the compositionsthemselves are identified in Table 2 below.

Samples of fuel emulsions were prepared by adding the emulsifiercomposition samples identified in Table 2 together with a diesel fuel,available from Petroplus, into a Turrax mixer operating on setting 1(11,000 rpm). Demineralised water was then added slowly. The sampleswere mixed for a further 20 minutes after completion of water addition.A proportion of each sample was transferred to a 100 ml crow measuringcylinder, which was filled to the 100 ml mark, to stand underobservation to determine the stability of the samples.

The samples of fuel emulsions are identified in Table 3 below and theresults of the observations are detailed in Table 4 below. TABLE 1Emulsifier Composition Components HLB Description Polymeric SurfactantHypermer A60* 6.0 Polyester non-ionic surfactant available from UniqemaHypermer A70* 6.0 Polyester non-ionic surfactant available from Uniqema.This product is a direct replacement for Hypermer A60 surfactant.Component a) Span 80* 4.3 Sorbitan monooleate available from UniqemaSpan 85* 1.8 Sorbitan trioleate available from Uniqema Component b)Tween 85* 11.0 POE (20) sorbitan trioleate available from Uniqema*Trade marks owned by the ICI group of companies.

TABLE 2 Emulsifier Compositions Span 80 Span 85 Tween 85 Hypermer A60Sample % wt % wt % wt % wt HLB EC1 95 5 4.4 EC2 90 10 4.5 EC3 80 20 4.6EC4 60 40 5.0 EC4a 58.8 41.2 5.0 EC5 10 90 6.5 EC6 20 80 7.0 EC7 30 707.5 EC8 40 60 8.0 EC9 76.5 13.5 10 5.4 EC10 54 36 10 5.5 EC11 65.2 34.85.0 EC12 54.3 45.7 6.0 EC13 4.3.5 56.5 7.0

TABLE 3 Fuel Emulsions Emulsifier Composition Diesel Water Sample % wt %wt % wt FE1  EC1 - 2.0% 88.0 10.0 FE2  EC2 - 1.6% 88.4 10.0 FE3  EC3 -1.2% 88.8 10.0 FE4  EC4 - 0.7% 89.3 10.0 FE4a EC4a - 0.7% 89.3 10.0 FE5 EC5 - 2.0% 88.0 10.0 FE6  EC6 - 2.0% 88.0 10.0 FE7  EC7 - 2.0% 88.010.0 FE8  EC8 - 2.0% 88.0 10.0 FE9  EC9 - 1.0% 89.0 10.0 FE9a  EC9 -2.0% 88.0 10.0 FE10 EC10 - 1.0% 89.0 10.0 FE10a EC10 - 2.0% 88.0 10.0FE11 EC11 - 1.0% 89.0 10.0 FE11a EC11 - 2.0% 88.0 10.0 FE12 EC12 - 1.0%89.0 10.0 FE12a EC12 - 2.0% 88.0 10.0 FE13 EC13 - 1.0% 89.0 10.0 FE13aEC13 - 2.0% 88.0 10.0

In Table 4, the observations are as follows:

-   a) “cloudy”=emulsion;-   b) “cream”=water rich layer at bottom of cylinder;-   c) “oil”=separated diesel layer at top of cylinder; and-   d) “water”=separated water layer at bottom of cylinder.

As fuel is drawn from the bottom of tanks supplying engines, thepresence of “water” at the bottom of the fuel emulsion is the mostdetrimental observation. It will be readily apparent that too high aproportion of water drawn into the engine will result in stoppage of theengine. Although the presence of “cream”, ie the water-rich layer, isnot particularly desired for the same reason, “cream” is still anemulsion containing diesel.

The observations in Table 4 were taken at regular intervals. Theobservations for Samples FE1 to FE4 were taken at 5, 7, 11, 13 and 15days; the observations of the Samples FE4a to FE13a were taken variouslyat 6, 9 and 13 days, 3, 7 and 11 days, 3, 7, 11 and 18 days and 3 and 11days. The columns for 7 and 11 days observations are the same throughoutthe table for ease of reference.

Samples FE1 to FE4 and FE4a were prepared on an equal cost basis, ie thecost of the amount of emulsifier composition in each sample issubstantially the same. It is to be noted opposite Samples FE4 and FE4athat they maintained the water in the fuel emulsion even though theywere present at a relatively low level. However, a significant amount ofoil separated from the emulsion.

Comparative Samples FE11 to FE13a show significant water separation evenafter only 3 days. TABLE 4 Fuel Emulsion Stability Observations SampleHLB 5 days 7 days 11 days 13 days 15 days FE1 4.4 1 ml oil 1 ml oil 1 mloil 1 ml oil 2 ml oil Cloudy to Cloudy to Cloudy to Cloudy to Cloudy tobottom bottom bottom bottom bottom FE2 4.5 <0.5 ml oil 0.5 ml oil 0.5 mloil 0.5 ml oil 2 ml oil Cloudy to Cloudy to Cloudy to Cloudy to Cloudyto bottom bottom bottom bottom bottom FE3 4.6 <0.5 ml oil <0.5 ml oil<0.5 ml oil <0.5 ml oil <0.5 ml oil Cloudy to Cloudy to Cloudy to Cloudyto Cloudy to bottom bottom bottom bottom bottom FE4 5.0 2 ml oil 3 mloil 5 ml oil 5 ml oil 7.5 ml oil Cloudy to Cloudy to Cloudy to Cloudy toCloudy to bottom bottom bottom bottom bottom Sample HLB 6 days 9 days 13days FE4a 5.0 1 ml oil 1.5 ml oil 1 ml oil 1 ml cream 1 ml cream 2 mlcream Sample HLB 3 days 7 days 11 days FE5 6.5 Trace oil Trace oil 1 mloil Cloudy to Cloudy to Cloudy to bottom bottom bottom FE6 7.0 Trace oilTrace oil 1 ml oil Cloudy to Cloudy to Cloudy to bottom bottom bottomFE7 7.5 Trace oil Trace oil 1 ml oil Cloudy to Cloudy to Cloudy tobottom bottom bottom FE8 8.0 Trace oil Trace oil 1 ml oil Cloudy toCloudy to Cloudy to bottom bottom bottom Sample HLB 3 days 7 days 11days 18 days FE9 5.4 <0.5 ml oil 1.0 oil Trace oil 2 ml oil <0.5 ml <0.5ml 4 ml cream 7.5 ml cream cream cream FE9a 5.4 <0.5 ml oil 1.0 oil 1 mloil 1 ml oil <0.5 ml <0.5 ml 1.5 ml 2 ml cream cream cream cream FE105.5 <0.5 ml oil 1.0 oil 1.5 oil 2 ml oil <0.5 ml <0.5 ml <0.5 ml 1 mlwater cream cream cream FE10a 5.5 <0.5 ml oil 0.5 oil 1.0 oil 1 ml oil<0.5 ml <0.5 ml <0.5 ml No water cream cream cream FE11* 5.0 1 ml oil 1ml oil 5 ml water 5 ml water FE11a* 5.0 No clear No clear oil oil 1 mlcream 1 ml cream FE12* 6.0 1 ml oil 1 ml oil 7 ml water 8 ml waterFE12a* 6.0 1 ml oil Trace oil 2 ml water 4 ml water FE13* 7.0 1 ml oil 3ml oil 8 ml water 9 ml water FE13a* 7.0 1 ml oil 2.5 ml oil 6 ml water 8ml water*Comparative examples.

EXAMPLE 2 Comparative Method

Samples EC1 to EC4 were each mixed in a beaker with diesel in theproportions shown in Table 5. To each fuel/emulsifier composition sampleCFE1 to CFE4 was added 0.25 g of demineralised water, mixing beingeffected by low shear stirring. The water was not dispersed in thediesel but remained as separate globules in the bottom of the beaker.TABLE 5 Comparative Fuel/Emulsifier Compositions Emulsifier CompositionDiesel Sample % wt % wt CFE1 EC1 - 2.0% 98.0 CFE2 EC2 - 1.6% 98.4 CFE3EC3 - 1.2% 98.8 CFE4 EC4 - 0.7% 99.3

This Example demonstrates that, even with very small quantities ofwater, low shear mixing is ineffective.

EXAMPLE 3 Comparative Method

Samples CFE5 to CFE8 were prepared using quantities of EC1 to EC4 asshown in Table 6. To each of those samples was added drop wise 100 g ofdemineralised water, mixing being effected by high shear stirring usinga Turrax stirrer on setting 1 (11,000 rpm). 20 g of each ofdiesel/emulsifier composition/water sample (Samples CFE5a to CFE8a) wasadded to 80 g of diesel; transferred to a 100 ml stoppered measuringcylinder; and the cylinder was inverted four times to mix the contentsthereof.

This resulted in a final percentage by weight concentration ofemulsifier composition as shown in Table 7. The observations on thesamples are shown in Table 7.

There was no water layer present in any of the samples although therewere significant levels of cream, ie a water rich layer, in the samples.This Example demonstrates that preparing a separate “master batch” offuel emulsion was not as effective as mixing the ingredients in a singlemixing operation as set out in Example 1. TABLE 6 ComparativeFuel/Emulsifier Compositions Emulsifier Composition Diesel Sample % wt %wt CFE5 EC1 - 20.0% 80.0 CFE6 EC2 - 16.0% 84.0 CFE7 EC3 - 12.0% 88.0CFE8 EC4 - 7.00% 93.0

TABLE 7 Comparative Fuel Emulsion Compositions % age concentration ofemulsifier Sample HLB composition 2 days 4 days 7 days 21 days CFE5a4.39 2.0   2 ml oil    2 ml oil TraceI TraceI oil*  1.5 ml  2.5 ml oil*13 ml cream cream   7 ml cream cream CFE6a 4.47 1.6   2 ml oil    2 mloil TraceI TraceI oil*  1.5 ml  1.5 ml oil* 13 ml cream cream   5 mlcream cream CFE7a 4.64 1.2   2 ml oil    2 ml oil TraceI TraceI oil*   1ml cream    1 ml cream oil* 12 ml   3 ml cream cream CFE8a 5.0 .0.7   1ml oil    2 ml oil 2.5 ml oil  7 ml oil <0.5 ml <0.03 ml 1.5 ml  8 mlcream cream cream cream*Very difficult to estimate as progressively cloudy with no clearinterface.

1. A fuel emulsion comprises a water-in-diesel emulsion containing anemulsifier composition in an amount effective to form a stable emulsion,the emulsifier composition comprising a polymeric non-ionic surfactanthaving hydrophilic and hydrophobic repeating units together with atleast one component selected from: a) fatty acid esters or partialesters of polyhydric alcohols; b) alkoxylated fatty acid esters orpartial esters of polyhydric alcohols; and c) alkoxylated primaryalcohols; the polymeric non-ionic surfactant and said at least onecomponent being selected such that the emulsifier composition has anhydrophile/lipophile balance value of at least
 4. 2. A fuel emulsionaccording to claim 1 which contains at least 70% by weight diesel and upto 25% by weight of water, the weight percentages being based on thetotal weight of the emulsion.
 3. A fuel emulsion according to claim 1comprising an amount of emulsifier composition in the range 0.1% to 4%by weight of the total weight of the composition; more preferably, anamount of emulsifier composition in the range 1% to 3% by weight; andespecially an amount in the range 1% to 2.5% by weight.
 4. A fuelemulsion according to claim 1 in which the emulsifier composition has anhydrophile/lipophile balance value of at least
 5. 5. A fuel emulsionaccording to claim 1 in which the emulsifier composition has anhydrophile/lipophile balance value of not more than 8 and, morepreferably not more than 7 and more especially not more than
 6. 6. Afuel emulsion according to claim 1 which comprises not more than 50% byweight, based on the total weight of the emulsifier composition, morepreferably between 1% and 30%, and more especially between 2.5% and 20%of the polymeric non-ionic surfactant in combination with at least oneof components a), b) and c).
 7. A fuel emulsion according to claim 1which comprises the polymeric non-ionic surfactant in combination withat least two of components a), b) and c).
 8. A fuel emulsion accordingto claim 1 which comprises the polymeric non-ionic surfactant incombination with components a) and b).
 9. A fuel emulsion according toclaim 1 in which the polymeric non-ionic surfactant is a polyester inwhich the hydrophilic units are polyoxyalkylene units and thehydrophobic units are long chain hydrocarbon residues.
 10. A fuelemulsion according to claim 1 in which component a) is a reactionproduct of one or more polyhydric alcohols and one or more fatty acids.11. A fuel emulsion according to claim 10 in which the polyhydricalcohol comprises alcohols having at least three hydroxyl groups.
 12. Afuel emulsion according to claim 10 in which the polyhydric alcohol isselected from glycerol and sorbitol.
 13. A fuel emulsion according toclaim 10 in which the fatty acid comprises a C12 to C24, straight orbranched chain, saturated or unsaturated acid.
 14. A fuel emulsionaccording to claim 10 in which the fatty acid comprises a C16 to C20straight chain acid.
 15. A fuel emulsion according to claim 10 in whichthe fatty acid is selected from stearic acid or oleic acid.
 16. A fuelemulsion according to claim 1 in which component b) is a reactionproduct of at least one component a) with an alkylen oxide.
 17. A fuelemulsion according to claim 1 in which component b) is a reactionproduct of at least one component a) with not more than 50 moles, andpreferably not more than 30 moles, of an alkylen oxide.
 18. A fuelemulsion according to claim 1 in which component c) is a reactionproduct of C₇-C₂₀, more especially from C₉ to C₁₅, primary alcohols ormixtures thereof with an alkylen oxide.
 19. A fuel emulsion according toclaim 1 in which component c) is a reaction product of C₇-C₂₀, moreespecially from C₉ to C₁₅, primary alcohols or mixtures thereof with notmore than 50 moles, and preferably not more than 30 moles, of an alkylenoxide.
 20. A fuel emulsion according to claim 1 comprising a primaryalcohol.
 21. A fuel emulsion according to claim 20 comprising a primaryalcohol selected from C₅ to C₁₅, more especially C₆ to C₁₂, primaryalcohols.
 22. A fuel emulsion according to claim 20 in which the primaryalcohol comprises up to 5% by weight, more preferably up to 3% byweight, of the emulsifier composition.
 23. An emulsifier composition foruse in fuel emulsions, which composition comprises a polymeric non-ionicsurfactant having hydrophilic and hydrophobic repeating units togetherwith at least one component selected from: a) fatty acid esters orpartial esters of polyhydric alcohols; b) alkoxylated fatty acid estersor partial esters of polyhydric alcohols; and c) alkoxylated primaryalcohols; the polymeric non-ionic surfactant and said at least onecomponent being selected such that the emulsifier composition has ahydrophile/lipophile balance value of at least
 4. 24. An emulsifiercomposition according to claim 23 having an hydrophile/lipophile balancevalue of at least
 5. 25. An emulsifier composition according to claim 23having an hydrophile/lipophile balance value of not more than 8 and,more preferably not more than 7 and more especially not more than
 6. 26.An emulsifier composition according to claim 23 which comprises not morethan 50% by weight, based on the total weight of the emulsifiercomposition, more preferably between 1% and 30%, and more especiallybetween 2.5% and 20%, of the polymeric non-ionic surfactant incombination with at least one of components a), b) and c).
 27. Anemulsifier composition according to claim 23 which comprises thepolymeric non-ionic surfactant in combination with at least two ofcomponents a), b) and c).
 28. An emulsifier composition according toclaim 23 which comprises the polymeric non-ionic surfactant incombination with components a) and b).
 29. An emulsifier compositionaccording to claim 23 in which the polymeric non-ionic surfactant is apolyester in which the hydrophilic units are polyoxyalkylene units andthe hydrophobic units are long chain hydrocarbon residues.
 30. Anemulsifier composition according to claim 23 in which component a) is areaction product of one or more polyhydric alcohols and one or morefatty acids.
 31. An emulsifier composition according to claim 30 inwhich the polyhydric alcohol comprises alcohols having at least threehydroxyl groups.
 32. An emulsifier composition according to claim 30 inwhich the polyhydric alcohol is selected from glycerol and sorbitol. 33.An emulsifier composition according to claim 30 in which the fatty acidcomprises a C₁₂ to C₂₄, straight or branched chain, saturated orunsaturated acid.
 34. An emulsifier composition according to claim 30 inwhich the fatty acid comprises a C₁₆ to C₂₀ straight chain acid.
 35. Anemulsifier composition according to claim 30 in which the fatty acid isselected from stearic acid or oleic acid.
 36. An emulsifier compositionaccording to claim 23 in which component b) is a reaction product of atleast one component a) with an alkylen oxide.
 37. An emulsifiercomposition according to claim 36 in which component b) is a reactionproduct of at least one component a) with not more than 50 moles, andpreferably not more than 30 moles, of an alkylen oxide.
 38. Anemulsifier composition according to claim 23 in which component c) is areaction product of C₇-C₂₀, more especially from C₉ to C₁₅, primaryalcohols or mixtures thereof with an alkylen oxide.
 39. An emulsifiercomposition according to claim 38 in which component c) is a reactionproduct of C₇-C₂₀, more especially from Cg to C₁₅, primary alcohols ormixtures thereof with not more than 50 moles, and preferably not morethan 30 moles, of an alkylen oxide.
 40. An emulsifier compositionaccording to claim 23 comprising a primary alcohol.
 41. An emulsifiercomposition according to claim 40 comprising a primary alcohol selectedfrom C₇-C₂₀, more especially C₉ to C₁₅, primary alcohols.
 42. Anemulsifier composition according to claim 40 in which the primaryalcohol comprises up to 5% by weight, more preferably up to 3% byweight, of the emulsifier composition.
 43. A method of making a fuelemulsion which comprises a water-in-diesel emulsion containing anemulsifier composition in an amount effective to form a stable emulsion,the emulsifier composition comprising a polymeric non-ionic surfactanthaving hydrophilic and hydrophobic repeating units together with atleast one component selected from: a) fatty acid esters or partialesters of polyhydric alcohols; b) alkoxylated fatty acid esters orpartial esters of polyhydric alcohols; and c) alkoxylated primaryalcohols; the polymeric non-ionic surfactant and said at least onecomponent being selected such that the emulsifier composition has anhydrophobe/lipophobe balance value of at least 4 and, more preferably atleast 5, wherein said method comprises, in a single mixing operation,introducing diesel and the emulsifier composition and then water into amixing vessel whilst subjecting the mixture to high shear mixing at aspeed and for a period sufficient to create the emulsion.